Percussive drill bit



Sept. 24, 1957 R. A. WYMAN PERCUSSIVE DRILL BIT Filed No 2. 1955 122062220? fioZerZ 4 212 222022 fliiorzze y.

2 Sheets-Sheet 1 R. A. WYMAN 2,807,443

PERCUSSIVE DRILL BIT Sept. 24, 1957 2 Sheets-Shegt 2 Filed Nov. 2. 1953 0&6'2' 2 didgzzzaa dZZorz'zy.

2,807,443 Patented Sept. 24, 1 957 ice 2,807,443 PERCUSSIVE'DRILL BIT Robert A. Wyman, Claremont, N. H., assignor to Joy Manufacturing Company, Pittsburgh, Pa, a corperation of Pennsylvania Application November 2, 1953, Serial No. 389,832 14 Claims. (Cl. 255--64) This invention relates to percussive rock bits and more particularly to such bits for drilling holes of larger than conventional diameters.

To increase the efiiciency of bits of the kind mentioned,

it is desirable not to have them have to cut away all the material of the full area of the hole bottom. Instead it is a great advantage to form an annular recess and break up the central core which the recess surrounds, rather than to pulverize the rock at the center of the forward end of a hole. Such an arrangement prevents problems in removal of the broken up material, and in the supply of cleansing or blowing fluids, and these are solved with the present invention.

It is an object of the invention to provide an improved rock bit of the percussive type. -It is another object of the invention to provide an improved percussive bit structure in which suitably disposed edges cut free peripherally a core of rock of substantial diameter, and a further edge or series of edges breaks up the central core. It is a further object to provide a bit of the character mentioned having improved blowing and cleansing fluid supply means. It is still another objectto provide an improved bit of the character mentioned having improved means for the escape of the material of the fractured core. It is still a further object to provide an improved bit of the character mentioned having improved means for effecting its assembly and providing for replacement or resharpening its constituent parts. Other objects and advantages will hereinafter appear.

In the accompanying drawings, in which one illustrative embodiment and a modification are shown,

Fig. 1 is a side elevational view of a bit in which the invention is incorporated, the same shown mounted. on hollow drill steel;

Fig. 2 is a front end view of the bit of Fig. l;

Fig. 3 is a central longitudinal section on the plane of the line 3-3 of Fig. 2;

Fig. 4 is a rear end view of the bit of Fig. 1;

Fig. 5 is a central longitudinal section on the plane of the line 5-5 of Fig. 2;

Fig. 6 is a transverse section on the planes of the line 6-6 of Fig. 5;

Fig. 7 is a front end view of a modified bit, and

Fig. 8 is a fragmentary section on the plane of section line 8-8 of Fig. 7, with some parts back of the section plane omitted and the inner bit shown in elevation.

Referring to the drawings, and first to the embodiment of the invention shown in Figs. 1-6, it will be noted that a bit structure 11 is shown at the forward end 12 of a drill steel. This bit structure includes a hollow bit body 13 and an inside bit 14. The bit body 13 may assume various shapes, but is here shown as comprising a frustoconical portion 15 of one taper, a shorter frusto-conical portion 16 of a smaller taper, and a plurality of cutting edges 17 at the forward end of the portion 16.

Within the body structure 11 is a recess or chamber 18 which includes as shown a generally circular inner of rearwardly disposed portion 20 to which access is had from in front through an opening 21 Which is generally circular in cross section, but which has a somewhat scalloped periphery as shown at 22, the scalloped periphery being due to the fact that between the edges 17 the circumferential wall of the portion 16 is somewhat reduced in thickness by grooving out to the full diameter of the chamber 20.

The body portion 13 is provided with a series of, as

here shown, flat bottomed cuttings escape grooves 25, one between each pair of cutting edges.

Holes 26 of substantial diameter-since they are cuttings-egress holes-extend obliquely outwardly from the rearward wall of the chamber 20 and open through the periphery. of the frusto-conical portion 15 in the same lines, as shown in Figs. 1, 2 and 3, from front to back, with the cutting edges.

The body portion 13 has a threaded socket 30 to cooperate with a threaded spud 31 on the forward end 12 of a drill steel.

seat 39 to receive the frusto-conical peripheral portion 40 of the internal bit 14. The bit 14 is shown as a cross bit, but the'number and disposition of its edges41 may be varied for best adaptability to the rock core to be disintegrated. The bit 14 has as shown an internally threaded socket 43 to cooperate with the connector por-.

tion 37.

The drill steel is shown as a hollow one and its for- .ward portion 12 has a central fluid passage 50 which opens into the counterbore 32. The connector element 35 has a central fluid passage 52 which communicates with a fluid passage 54 in the bit element 14.

As shown in the drawings, and particularly in Figs. 1, i

4, 5 and 6, a series of radially outwardly diverging passages 56 extend from the counterbore 32, from points in the latter radially outwardly of the head 36 into the for ward ends of the grooves 25 where they have mouths 57.

The edges 17 are preferably provided by radially extending hard-metal inserts 6t), suitably held in position,

and the edges 41 may also be provided by hard metal inserts, these numbered 62. It is important to note that the edges 41 are set well back of the edges 17, indeed well back of the bases of the latter, as illustrated.

As illustrated in Figs. 7 and 8, substantial modifications are possible, and in these figures the radial cutting edges are replaced by hard metal insert equipped alternate inner and outer chopping edges respectively numbered v 63 and 64, the cleansing fluid passages 56' are made more numerous and smaller in diameter and one opens between each pair of chopping edges, and, the total number of chopping edges being shown as ten, the vent passages 26 are here shown as being five, equally spaced about the periphery of the bit.

In both forms illustrated the improved bit structure will form an annular opening, in the one case by cutting, in the other primarily by chopping, and since'the edges 41 are set well back of the edges 17 (or 63, 64) there' will be formed a projecting circular core of rock of substantial projection from the zone in which the cutting or chopping edges, as the case may be, are operating. When this is reached by the edges 41, the projecting core will be broken up into pieces of substantial size, instead of being pulverized, and the fragments will be blown or washed out of the inside of the space surrounded by the cutting or chopping edges through the passages 26. The

supply of fluid through the central passages in the bit There is shown at the forward end of the socket 30 a counterbore 32 and just ahead of the structure will furnish at least most of what is required, but the fluid passing through the passages 56 will aid in keeping the forwardmost portion of the hole clear and in blowing cuttings and larger particles through the grooves 25,and up the, hole around the drill steel.

The biti structure may. be readily disassembled for sharpening or thezreplacement of parts, and will permit the formation of a hole of large diameter without the larger loss of energy in pounding on a central pad of rock dust that would, be present with a bit of like diameter but conventional construction. It will of course be understood that the bit will commonly be turned step by step on its axis so that the various edges may engage a fresh point each time a blow is transmitted to the steel.

, While there is in this application specifically described one form and a modification which the invention may assumein practice, it will be understood that this form and modification .of the same are shown for purposes of illustration, and that the invention may further be modified and embodied in various other forms. without departingfromjtsspiritor the scope of the appended claims.

What, is claimed is: p

1. A percussive drill bit comprising a main body having a forward end presenting an annularly arranged series offorwardlyprojecting edges and having a central recess extending to the rear of said forwardly projecting edges, and also having a percussive disintegrating device for a core of rock out free peripherally by said annularly ar' ranged, series of forwardly projecting edges, said percussivedisintegrating device having its forward end within said, recess but ,to the rear of said annularly arranged series of forwardly projecting edges, said body having a socket in its rearward end for interlockingly engaging a drill steel, and said body having another socket forward of said first socket and communicating with the forward end of the, latter and receiving said percussive disintegrating device, there being a shoulder between said sockets, and a threaded spud having a head engaging said shoulder andhavirig an interlocking connection with said percussive disintegrating device for holding the latter in the scqondsocket with its. forward end in said recess.

2. A percussivedrill bit according to claim 1 in which a. cleansing fluid passage, opens. from the first socket through the spud and thepercussive disintegrating device into said. recess.

3. A percussive drill .bit according to claim 2 in which said main, body has cleansing fluid passages extending from said first socket forwardly through the walls of said body and opening near the forward end thereof.

4. A percussive drill bit according to claim 2 in which said main body haslongitudinally extending grooves upon its periphery between said forwardly projecting edges and has cleansing fluid passages extending from said first socket i forwardly through the walls of-said body and opening near the forward end thereof.

5. A percussive drill bit according to claim 2 in which said main body has longitudinally extending grooves upon its periphery between said forwardly projecting edges and cleansing fluid passages extending from said first socket forwardly through the walls of said body and op ning into said grooves.

6. A percussive drill bit according to claim 2. in which said mainbodyhas cleansing fluid passages extending,

from said first socket forwardlythrough the walls of said body and openingnear the forward end thereof at points spaced circumferentially between the forwardly projecting cutting edges.

7. Apercussivedrillbit comprising a body having a forward end presentingan annularly arranged series of forwardly projecting edges and. further comprising, co. aria] with, but to the rear of said forwardly projecting edges, a percussive disintegrating device, said body having a plurality of grooves extending longitudinally peripheral-ly thereof, one, between each pair of adjacent edgesoblique passages for the discharge to its periphery of rock broken by said percussive disintegrating device, and other oblique passages for cleansing fluid opening into said grooves.

8. A percussive drill bit comprising a body having a forward end presenting an annularly arranged series of forwardly projecting edges and further comprising, coaxial with, but to the rear of said forwardly projecting edges, a percussive distintegrating device, said body having a plurality of grooves extending longitudinally peripherally thereof one between each pair of adjacent edges, oblique passages for the discharge to its periphery of rock broken by said percussive disintegrating device, and other oblique passages for cleansing fluid opening into said grooves, said first and second mentioned oblique passages alternating about the periphery of the bit.

9. In combination, in a percussive drilling implement, an outer bit element having a series of forwardly projecting edges arranged in an annulus and further having a recess rearward and inward of said edges, a central bit element having forwardly projecting; edges and mounted centrally within said outer bit element with its. edges; projecting into said recess. but rearward of Said. series. of forwardly projecting edges, passage means extending outwardly from said, recess for discharging to the exterior of said outerbit element cuttings produced by said central bit element, means for conducting cleansing fluid to said several edges including a central passage extending through said central bit element and; forwardly extending passages arranged in said outer bit element to the outside of said central bit element, and means for attaching said outer bit element to a drill steel.

10. In combination, in a percussive drilling implement, a bit element having centrally arranged in, its rearward. end a threaded socket for the reception of the threaded end of a drill steel, at its forward end a recess and an annularly disposed series of edges surrounding at. least the forward end of said recess, rearwardly of said recess a socket, for the reception of a central bit, and between said sockets a rearwardly facing shoulder for engagement with the head, of a holding element for a central bit, said bit element having, spaced outwardly from said second recited socket, outwardly and, rearwardly extended cut-. tings egress passages connecting the recess at its forward end with the bit element periphery and outwardly and forwardly extending cleansing fluid supply passages connected with said threaded socket and opening at their forward ends through the periphery of said bit element.

11. In combination, in a percussive drilling imPiQInent, an annular series of forwardly facing edges, central edges lying inwardly and rcarwardly of said annular series of edges, supporting means for said annular series, of edges providing a forwardly opening annular reccss surrounding said central edges and having outwardly and rearwardly extending passages connecting said annular recess with the periphery of said supporting means, a socket at the rearward end of the implement, and forwardly extending cleansing fluid conducting passages extending forwardly from said socket and terminating at their forward ends to the outside of saidannular recess.

12. In combination, in a percussive drilling implement, an outer bit element having an annularly arranged series of edges at its forward end, a recess surrounded by said series of edges, a. tapering socket back of said recess, a rearwardly facing shoulder back of said socket, a threaded element having a head engaging said shoulder and a threaded portion extending forwardly along the axis of said tapering socket, and an inner bit element having cutting edges within said recess, a tapering surface fitting said tapering socket and a threaded portion engaged by said threaded element.

13. In combination, in a percussive drilling implement, an outer bit element having an annularly arranged series vof edges at its forward end, a recess surrounded by said a head engaging said shoulder and a threaded portion extending forwardly along the axis of said tapering socket, and an inner bit element having cutting edges within said recess, a tapering surface fitting said tapering socket, and internally threaded to connect with said threaded portion of said threaded element. a

14. In combination, in a percussive drilling implement, an outer bit body having a circumferentially arranged series of spaced, forwardly extending edges surrounding a recess, an inner bit having cutting edges projecting forward into said recess but arranged rearward of said series of edges, cuttings discharge passages opening through the periphery of said outer bit body and communicating at their forward ends with said recess, and cleansing fluid conducting passages opening at their forward ends between said forwardly extending edges on said outer bit body.

References Cited in the file of this patent UNITED STATES PATENTS Foust July 25, Scott Apr. 19, Howard Sept. 15, Wise et al. May 12, Zimmerman Jan. 30, Baker Mar. 22,

FOREIGN PATENTS Switzerland Nov. 1, Sweden Aug. 30, Germany Jan. 4, 

